Question

How many terms of the following sequence should be taken so that the sum is zero? a) 18, 16, 14,... b) 65, 60, 55,... c) 27,24,21,...

Answer 1

Answer:

an=a+(n-1)d

a) a=18, d=16-18= -2

an=a+(n-1)d

0=18+(n-1)-2

18-2n+2=0

-2n= -20

n= -20/-2=10

b)a=65, d= -5

an=a+(n-1)d

0=65+(n-1) -5

0=70-5n

-5n= -70

n=16

c)a=27, d= -3

an=a+(n-1)d

0=27(n-1)-3

0=30-3n

-3n= -30

n=10

Step-by-step explanation:

Answers:

a)10th term

b)16th term

c)10th term